1. Field of the Invention
The present invention relates to towing accessories and, more particularly without limitation, to tow bars for connecting a towed vehicle to a towing vehicle.
2. Description of the Related Art
A tow bar is generally used for connecting a towing hitch arrangement 2 of a vehicle to be towed, sometimes referred to herein as a towed vehicle 4, to a towing hitch arrangement 6 of a towing vehicle 8. For applications wherein the towed vehicle will be towed at a speed sufficient to move with the flow of traffic on a public roadway, the tow bar, which connects the front end of the towed vehicle to the rear end of the towing vehicle, generally has two tow bar legs with the front ends of the tow bar legs forming the apex of an isosceles triangle and the rear ends of the tow bar legs spaced apart and forming the sides of the triangle. The triangular configuration causes the towed vehicle to closely track the towing vehicle, both along straightaways and around corners.
For tow bar applications, such as where heavy, massive equipment will be moved a relatively short distance, such as where an airliner is to be backed away from a terminal for example, the tow bar generally has only one tow bar leg. For such applications, one end of the tow bar leg may be connected to the front end of the vehicle to be moved and the other end of the tow bar leg connected to the front end of the moving vehicle so the operator of the towing vehicle can face the vehicle to be moved and can carefully observe the response of the towed vehicle as it is being slowly moved by the towing vehicle.
Tow bars for moving towed vehicles rapidly along public roadways must be designed to accommodate variations in attitude that inherently exist between the towing and towed vehicles, which variations are constantly and continuously changing. One such variation in attitude between the vehicles is the instantaneous elevation of the towing vehicle relative to the instantaneous elevation of the towed vehicle. A related variation in attitude between the vehicles is the instantaneous ascent/descent orientation of the towing vehicle relative to the instantaneous ascent/descent orientation of the towed vehicle. Both of these related variations in attitude can be accommodated by apparatus designed to accommodate rotations between the towing and towed vehicles about a transverse, horizontal axis, sometimes referred to as the “pitch” axis, see the “x”-axis in FIG. 1.
Another such variation in attitude between the vehicles is the instantaneous horizontal direction in which the towing vehicle is traveling relative to the instantaneous horizontal direction in which the towed vehicle is traveling, such as when the towed vehicle is being pulled around an unbanked corner for example. This phenomenon, sometimes referred to as “yaw”, can be accommodated by apparatus designed to accommodate rotations between the towing and towed vehicles about a vertical axis, see the “y”-axis in FIG. 1.
Finally, another such variation in attitude between the vehicles is the instantaneous sidewise tilt of the towing vehicle relative to the instantaneous sidewise tilt of the towed vehicle, such as the rocking motion which occurs when traversing uneven or rough pavement for example. This phenomenon, sometimes referred to as “roll”, can be accommodated by tow bar apparatus designed to accommodate rotations between the towing and towed vehicles about a longitudinal, horizontal axis, see the “z”-axis in FIG. 1.
During actual towing procedures, all combinations of the pitch, yaw and roll phenomena are continuously occurring and changing. Prior art is replete with tow bar designs that have been developed in an attempt to accommodate these phenomena, some of those designs being more successful than others. For example, a ball hitch/ball hitch receiver combination securing a tow bar to a towing vehicle can theoretically accommodate all three of the pitch, yaw and roll criteria. Although the ability of such a combination to accommodate yaw is encouraging, unfortunately the ability of such a combination to accommodate either pitch or roll is extremely limited, where failure to closely abide by those limitations can produce disastrous and even fatal results.
A commonly used arrangement involves using a conventional receiver hitch in combination with a square tube. Although such an arrangement may be convenient for connecting a tow bar to a towing vehicle, this type of connection by itself provides absolutely no ability to accommodating any one of the three pitch, yaw or roll criteria. As a result, the tow bar and/or the connections between the tow bar and the towed vehicle must be relied upon to provide a solution for minimizing the potentially potential detrimental effects of these criteria.
At the same time, an ability to apply such rotations could be very useful while connecting a tow bar to a towed vehicle. Typically, a tow bar is first connected to a towing vehicle 8 followed by connecting the tow bar to the towed vehicle. It is difficult, if not impossible, to perfectly align a towed vehicle with, and perfectly space the towed vehicle from, a towing vehicle so the tow bar legs 18 can be easily and conveniently connected to the towed vehicle. Many towing hitch arrangements of towed vehicles require precise fore-to-aft, horizontal, and angular alignment of the two tow bar leg connectors with the mating connectors of the towing hitch arrangement of the towed vehicle so pivot pins can be inserted horizontally through horizontally-aligned orifices of those mating connectors while the tow bar mating parts are physically held in place relative to those of the towed vehicle. Such activity can be extremely stressful, sometimes requiring the efforts of more than one person, such as when connecting massive tow bars used to tow heavy military equipment for example. Such stress and effort could be reduced considerably if each of the tow bar leg connectors could be individually articulated in close proximity to the towed vehicle so each tow bar leg connector could be easily and conveniently mated with the towing hitch arrangement of the towed vehicle while the pivot pins are inserted.
What is needed is a tow bar having orthogonally-articulated tow bar leg connectors for connecting tow bar legs to the towing hitch arrangement of a towed vehicle.
Some prior art tow bars are designed to provide a storage capability for the tow bar when the tow bar is not being used. Some of those designs are for tow bars that remain connected to the towed vehicle, such as by pivoting the tow bar legs upwardly at the front end of the towed vehicle and securing the tow bar legs in an upright configuration. Needless to say, the result is very unsightly and tends to obstruct forward vision when the towed vehicle is subsequently being driven on its own. This arrangement is not efficient for situations wherein the towing vehicle needs to use the tow bar to pull other towed vehicles.
Accordingly, other prior art tow bars are designed to provide a storage capability wherein the tow bar remains connected to the towing vehicle, such as by pivoting the tow bar legs upwardly or sidewise at the rear end of the towing vehicle and securing the tow bar legs in that configuration by hooking the tow bar legs to another part of the tow bar. Unfortunately, it is not uncommon for such arrangements to become unhooked, especially when the towing vehicle travels over very rough terrain, such as railroad tracks, potholes, and the like.
What is needed is a tow bar wherein the tow bar legs have self-storing capability.